The NHS cannot, and never has been able to, offer every treatment to everyone who needs it.

The NHS is funded from taxes, and it spends more than £42bn every year - £779 for every person in the UK. But it is not a bottomless pit of funds and some treatments have to be restricted.

Raising taxes to pay for every possible need is politically unthinkable, as it would require a massive increase in income tax to raise enough revenue to make a significant difference to spending.

This means some treatments have to be restricted, or rationed.

The media hype over the anti-impotence drug Viagra forced the issue out into the open.

The government has restricted the circumstances in which people will be prescribed the drug.

Responsibility

The British Medical Association wants the government to accept responsibility for rationing decisions and to consult the public over which treatments should be restricted on the NHS.

This would require a national policy - at the moment health authorities make the decisions on drug rationing on an individual basis.

This leads to accusations that care is being delivered by postcode since patients living under one health authority are denied a treatment available to those living under another.

The issue of rationing has also come to the fore due to the setting up of primary care groups later this year, when GPs will take over responsibility for commissioning care for their patients.

In a January 1999 survey of GPs, conducted by Doctor magazine, one in five said they knew patients who had suffered harm as a result of rationing.

More than 5% of the 3,000 surveyed also said they knew of patients who had died as a result of being denied treatment on the NHS.

Expensive treatments

One of the most controversial rows over rationing concerns beta interferon, a treatment for multiple sclerosis.

The full effectiveness of the drug has yet to be established, and because it is very costly - approximately £10,000 per patient per year - some health authorities are reluctant to allow doctors to prescribe it.

Another example is a drug used in the treatment of ovarian cancer, Taxol, which has been licensed for use in the UK since mid-1998.

Viagra has been restricted to certain patients

It costs £1,500 per injection and the average course requires six of these.

There are two studies that show the drug extends a patient's life by a year, but this is not enough evidence to justify prescribing it for everyone with ovarian cancer.

Marilyn Bush had the disease but was able to get the treatment because her private health care insurance agreed to pay for it.

She said: "Could you imagine how you would feel if you knew you could not possibly find the money for a drug you needed?"

Popular treatments

The case of Viagra is different, however. At an NHS price of £4.84 a pill, it is nowhere near as expensive as beta interferon.

Beta Interferon is a controversial MS treatment

But the government placed a temporary ban on NHS prescriptions of the drug because it feared so many patients would want it.

The ban is to remain in place until guidelines have been formulated to define who should get Viagra and who should be denied it. The guidance is due to be published in January 1999.

In future, the National Institute for Clinical Excellence will issue guidance for a whole range of treatments.

In the meantime, however, it is up to individual health authorities to set priorities and to decide who is eligible for treatment.

Health authority guidelines

Dr Gordon Rustin, who treated Ms Bush, is familiar with the implications of local priority setting.

"Some health authorities have made special funding available just for patients who fit into certain clinical trials and some health authorities have said they will not provide any extra funding for Taxol."

Dr Rustin said that before he sees a patient he has to check their postcode to see which health authority pays for their treatment. He says he can only then prescribe the drug if he knows the authority will fund it.

He said authorities have to make a crude calculation.

"They want to show that we can improve duration of life with a new drug and they then try to calculate the extra duration of life," he said.

"If you get an extra year of life for less than £10,000 then it is generally considered that that is a reasonable buy."